Can someone explain this function within functiong thing

Question

def add(x, y):
return x + y
def do_twice(func, x, y):
return func(func(x, y), func(x, y))

a = 5
b = 10
print(do_twice(add, a, b))

Answer 1

By making func add what it's now reading is:
Return add(a+b,a+b)

Everywhere you use the word func, has become add.

Answer 2

u r calling the function pointer with given parameters, first the most inner calls are made, then u get to make the last outter call.